Sugars fermented byBifidobacterium infantis ATCC 27920 in relation to growth and α-galactosidase activity

Summary The ability of Bifidobacterium infantis ATCC 27 920 to ferment glucose, galactose, lactose, melibiose and raffinose was investigated with respect to -galactosidase (-d-galactoside galactohydrolase, E.C. 3.2.1.22). The sugars were tested at three concentrations: 0.5, 1.0 and 2.0%. The growth of B. infantis was slower on glucose compared with the other sugars. The highest specific growth rate was observed on melibiose followed by lactose. High cell numbers could be rapidly obtained on galactose-containing sugars. For each carbohydrate, enzyme activity was maximal at the end of the exponential phase and the highest specific -galactosidase activities were recorded on the two -1,6 galactosaccharides (melibiose and raffinose: 3.0 and 4.5 nkat · 10⁹ colony-forming units, respectively).Contribution no. 186 from the Food Research and Development Centre Offprint requests to: D. Roy     

EMG power spectra of elbow extensors during ramp and step isometric contractions

The goal of the present study was to compare electromyogram (EMG) power spectra obtained from step (constant force level) and ramp (progressive increase in the force level) isometric contractions. Data windows of different durations were also analysed for the step contractions, in order to evaluate the stability of EMG power spectrum statistics. Fourteen normal subjects performed (1) five ramp elbow extensions ranging from 0 to 100% of the maximum voluntary contraction (MVC) and (2) three stepwise elbow extensions maintained at five different levels of MVC. Spectral analysis of surface EMG signals obtained from triceps brachii and anconeus was performed. The mean power frequency (MPF) and the median frequency (MF) of each power spectrum were obtained from 256-ms windows taken at 10, 20, 40, 60 and 80% MVC for each type of contraction and in addition on 512-, 1024- and 2048-ms windows for the step contractions. No significant differences (P greater than 0.05) were found in the values of both spectral statistics between the different window lengths. Even though no significant differences (P greater than 0.05) were found between the ramp and the step contractions, significant interactions (P less than 0.05) between these two types of contraction and the force level were found for both the MPF and the MF data. These interactions point out the existence of different behaviours for both the MPF and the MF across force levels between the two types of contraction.     

Characterisation of two differently processed forms of human recombinant factor IX synthesised in CHO cells transformed with a polycistronic vector

A stable transformed cell line constitutively expressing human factor IX has been established. Wild-type Chinese hamster ovary cells (CHO cells) were transformed using a polycistronic expression vector carrying a previously isolated factor IX cDNA and a selection gene encoding the Escherichia coli xanthine-guanine phosphoribosyl transferase. One clone, CHO 622.4, contains a high number of genomically integrated plasmids and secretes 1-3 mg factor IX l-1 day-1 into the culture medium with a biological activity ranging from 25% to 40%. The recombinant molecule was purified either by conventional chromatography or by immunoaffinity chromatography using antibodies specific to a calcium-induced factor IX conformer. The purified recombinant protein migrates as a single band with the same mobility as that of natural factor IX on SDS/polyacrylamide gels. N-terminal sequencing shows tow differently processed forms of recombinant factor IX: whereas the majority of the zymogen is correctly processed, approximately 20% of the purified recombinant molecule contains an 18-amino-acid NH2-extension corresponding to the precursor form of factor IX. Analysis of the 4-carboxyglutamic acid content indicates a high but incomplete carboxylation (70%) of the recombinant molecule as compared to natural factor IX. The carbohydrate composition of both the natural and recombinant molecules has been determined. Both molecules have a N-glycan structure of similar complexity, indicating that factor IX contains all the information to direct the same glycosylation pattern in human liver cells and in an unrelated cell line such as CHO-K1.     

L-649,923, sodium (beta S*, gamma R*)-4-(3-(4-acetyl-3-hydroxy-2-propylphenoxy)-propylthio)- gamma-hydroxy-beta-methylbenzenebutanoate, a selective, orally active leukotriene receptor antagonist

L-649,923, Sodium (beta S*, gamma R*)-4-(3-(4-acetyl-3-hydroxy-2-propylphenoxy)propylthio)- gamma- hydroxy-beta-methylbenzenebutanoate is a selective and competitive inhibitor of [3H]leukotriene D4 (Ki value of 400 nM) and to a lesser extent [3H]leukotriene C4 (Ki value of 8.6 microM) binding in guinea-pig lung homogenates. Functionally, it selectively antagonized contractions of guinea pig trachea induced by leukotriene C4, D4, E4, and F4 but not those induced by acetylcholine, histamine, serotonin, prostaglandin F2 alpha, or U-44069 (stable endoperoxide analogue). Schild plot analysis indicated a competitive inhibition of contractions of guinea-pig ileum induced by leukotriene D4 (pA2 8.1) and contractions of guinea-pig trachea induced by leukotrienes E4 and F4 (pA2 7.1 and 6.9, respectively). In contrast, contractions of guinea-pig trachea induced by leukotrienes C4 (pA2 7.2; slope 0.6) and D4 (pA2 7.2; slope 0.7) were inhibited in a noncompetitive fashion. In vivo, intravenously administered L-649,923 selectively blocked bronchoconstriction induced in anesthetized guinea pigs by leukotriene C4 and D4 (ED50 values i.v. 0.38 and 0.26 mg/kg, respectively) but not that induced by histamine, arachidonic acid, serotonin, U-44069, or acetylcholine. Following intraduodenal administration, L-649,923, blocked leukotriene D4 induced bronchoconstriction (5 and 10 mg/kg). The present findings indicate that selective antagonists, such as L-649,923, may be useful for defining the role of leukotrienes in diseases such as bronchial asthma.     

L-648,051, sodium 4-[3-(4-acetyl-3-hydroxy-2-propylphenoxy)- propylsulfonyl]-gamma-oxo-benzenebutanoate: a leukotriene D4 receptor antagonist

L-648,051, sodium 4-[3-(4-acetyl-3-hydroxy-2-propylphenoxy) propylsulfonyl]-gamma-oxo-benzenebutanoate is a selective and competitive inhibitor of [3H]leukotriene D4 (KB value of 4.0 microM) and to a lesser extent [3H]leukotriene C4 (Ki value of 36.7 microM) binding in guinea pig lung homogenates. Functionally, it selectively antagonized contractions of guinea pig trachea induced by leukotrienes C4, D4, E4, and F4 in concentrations that did not antagonize contractions induced by acetylcholine, histamine, serotonin, prostaglandin F2 alpha, or U-44069 (endoperoxide analogue). Schild plot analysis indicated that L-648,051 competitively antagonized contractions of guinea pig ileum induced by leukotriene D4 (pA2 7.7) and contractions of trachea induced by leukotrienes D4, E4, and F4 (pA2 7.3, 7.4, and 7.5, respectively). Contractions of guinea pig trachea induced by leukotriene C4 were inhibited in a noncompetitive fashion (Schild plot slope, 0.45). Developed contractions of trachea induced by the leukotrienes were rapidly reversed by L-648,051 greater than FPL-55712 greater than L-649,923. Intravenous L-648,051 selectively blocked bronchoconstriction induced in anaesthetized guinea pigs by intravenous leukotrienes C4, D4, and E4 but not that induced by arachidonic acid, serotonin, U-44069, or acetylcholine. The compound displayed poor activity following intraduodenal administration. The profile of activity for L-648,051 indicates that it may be a useful topical agent for studying the role of leukotrienes in diseases such as bronchial asthma.     

Treatment of dialysis membranes for simultaneous dialysis and concentration

Dialysis membranes used for simultaneous dialysis-concentration required pretreatment to remove uv-absorbing compounds leached from the membranes and to reduce the absorption of protein to the membranes. This was accomplished with sodium carbonate and ethanol or with "sulfur-removal solutions." Protein determinations were made with a micro-Bradford protein reaction and with uv absorbance at 280 nm. Soluble membrane components contributed to aberrant uv spectra and altered the ratio of 280/260-nm absorbance. Simultaneous dialysis and concentration in the micro protein dialyzer-concentrator apparatus, combining aspects of thin-layer dialysis and ultrafiltration, resulted in rapid removal of salts from the protein solutions. Prior treatment of membranes reduced uncertainties in retentate recoveries, eliminated uv-absorbing components of membranes, and improved recoveries of protein.     

Isolation of pituitary fibroblast growth factor by fast protein liquid chromatography (FPLC): partial chemical and biological characterization

Bovine pituitary fibroblast growth factor has been purified 222,000-fold to homogeneity by a combination of differential salt extraction, gel filtration, and ion exchange chromatography on Mono S column. Pituitary FGF is a single-chain polypeptide with an apparent molecular mass of 15,800 and an isoelectric point of 9.6. It is highly active in triggering the proliferation of bovine and human vascular endothelial cell [half-maximal stimulation at 23-40 pg/ml (1.5-2.6 pM) and saturation between 140 and 280 pg/ml (9.3-18.6 pM)]. It displays a similar activity on bovine vascular smooth muscle cells, corneal endothelial cells, granulosa and adrenal cortex cells, and rabbit costal chondrocytes.     

Evolution of the primate beta-globin gene region. High rate of variation in CpG dinucleotides and in short repeated sequences between man and chimpanzee

A 5500 base-pair fragment including the beta-globin gene downstream from codon 122 and about 4000 base-pairs of its 5' flanking sequence was cloned from chimpanzee DNA and thoroughly sequenced before being compared with the corresponding human sequence: 88 point differences (83 substitutions and 5 deletions or insertions of 1 base-pair) were detected as well as seven more important deletion/insertion events. These changes occur preferentially in two kinds of structure. First, 40% of the CpG dinucleotides present in either human or chimpanzee sequences are affected by nucleotide variations. This corresponds to a divergence level considerably higher than that expected. Second, most short repeated sequences found in the 5' extragenic sequence are involved in mutational events (amplification or contraction of the number of basic motifs as well as point substitutions or deletions/insertions of 1 base-pair). Considering the very low level of nucleotide sequence divergence between these two closely related species, our data provide direct evidence for CpG and tandem array instability.     

Whole-cell antigens of members of the sulfate-reducing genus Desulfovibrio

Antisera have been developed against the wholecell antigens of Desulfovibrio africanus Benghazi and Walvis Bay, D. vulgaris Hildenborough, D. salexigens British Guiana, D. gigas, and D. desulfuricans Essex 6. An enzymelinked immunoadsorption assay (ELISA) was developed to measure the reaction of these antisera with the homologous and heterologous antigens. The ELISA method demonstrated a reaction between pre-immune sera and cells of D. africanus, D. gigas and D. desulfuricans, suggesting the presence of a lectin-like substance on these cell surfaces. Extensive cross-reactions were seen between the antisera and heterologous cells, suggesting the sharing of a number of surface antigens amongst the Desulfovibrio. However, the pattern of these cross-reactions was different from that observed for an ELISA reaction developed for the cytochrome c₃ from various Desulfovibrio.Abbreviation ELISA enzyme-linked immunoadsorption assay